Once upon a time: Incredibly serious director Marty DiBergi sets out to make a documentary about the incredibly stupid heavy metal band Spinal Tap. But as he follows them around on their American comeback tour, they're plagued by an unending array of disasters, including exploding drummers, interfering girlfriends, a booking at a nearly empty Air Force base and a Stonehenge set that turns out to be only 18 inches tall.

Inappropriate material: Definitely for teens — this was rated R when it was released, for strong language and sexual innuendo. Most of that is simply silly, though, and there's no sex or violence.

Why kids will like it: Because although entire genres of pop have been invented in the nearly 30 years since this movie came out, the sweet pampered idiocy of rich musicians hasn't changed a bit — the routines about sexist album covers, ridiculous lyrics and amps that "go to 11" still connect. Are the jokes stupid? Sometimes, yeah. But as the Tap's own David St. Hubbins would say, "It's such a fine line between stupid and... clever."

Why adults will like it: At the time, this was hailed as a wild new film from director Rob Reiner (who also plays DiBergi). What critics didn't realize then was that it was really a dry run for Christopher Guest and crew — trying out an improv-and-mockumentary format that would result in such hysterical modern comedies as "Waiting for Guffman" and "A Mighty Wind." You can watch the gang actually figuring it all out here — when you're not spotting the offbeat cameos (Anjelica Huston?) or banging your head to hits from the band's "Smell the Glove."

Fun trivia: Still a go-to DVD for many rock bands on tour, although the reaction has always ranged from rueful recognition (members of Dokken and the Misfits said it could have been about them) to outright denial (Eddie Van Halen and Steven Tyler didn't think it was funny, at all). A confused Ozzy Osbourne — is that redundant? — thought it was about a real band, and nearly 30 years later, some viewers still don't get the joke (although, to be fair, McKean, Guest and Shearer can play, and did do a few brief gigs).

Teachable moments: For all the comedy, its seriously addled characters may be the most effective "This is your brain on drugs" message ever. But if you really want to scare your kids, get out your old Whitesnake albums. Or make them watch Alec Baldwin in "Rock of Ages."

Double features: If you're in the mood for another music parody, Eric Idle's fab-faux documentary "All You Need Is Cash" is an absolutely brilliant takeoff on Beatlemania; if you feel like more Guest and Co., "Best in Show," about neurotic dog breeders, is an easy one for teens to embrace.